1. Field of the Invention
This invention concerns a novel phosphorus-based reaction product and its use as an antioxidant and antiwear additive in lubrication oils, particularly automatic transmission fluids. The novel additive surprisingly does not attack silicone-based seals.
2. Description of Related Art
Phosphorus-based lubrication oil additives are known to attack silicone-based seals. In particular, laboratory studies indicate that dialkyl hydrogen acid phosphates of the type ##STR1## cause deterioration of silicone-based seals when used in lubrication oils such as automatic transmission fluids ("ATF"). However, dialkyl hydrogen acid phosphates of the type described above are effective-antiwear agents. Therefore, it would be desirable to have a similar antiwear agent which is not aggressive to silicone-based seals when used in lubrication oils, particularly ATF systems.
This invention remedies the silicone-seal deterioration problem by providing a sulfur-containing phosphate ester reaction product. This reaction product is not only an effective antiwear additive but also a surprisingly nonaggressive additive to silicone-based seals when used in lubrication oil systems. Additionally, the reaction product of this invention is an excellent antioxidant.